Hi Adalid Bori,
From the looks of that error message, the "Sign in again" prompt is almost certainly being triggered by a specific Sign-in frequency setting within your Conditional Access policies.
I’d suggest heading into the Microsoft Entra admin center under the Protection tab to check if a session policy is being applied too aggressively to that user’s specific group. If the cloud settings appear correct, the issue is usually just a stale or corrupted local authentication token, so having the employee clear their Windows Credential Manager and then re-authenticating through the "Access work or school" section in the system settings should resolve the loop.
It is likely just a mismatch between the device's local session and the tenant's policy requirements rather than a broader system failure.
Here’s the link to the Microsoft Learn documentation for managing session lifetimes. It covers exactly how to configure the sign-in frequency in Entra ID, which should help you resolve that repetitive prompt issue. I’d recommend checking the "Periodic reauthentication" settings first, as that's the most likely culprit for this kind of behavior: https://learn.microsoft.com/en-us/entra/identity/conditional-access/howto-conditional-access-session-lifetime
Best regards,
Tracy.